Dry valve stations are used to separate the water supply from the dry pipework as well as for issuing an alarm in case of a release. Dry pipeworks are used particularly in cases where the pipework cannot be filled with water because there is a risk of freezing. These pipeworks are generally filled with pressurized air. In case of a fire, the pipework must be vented rapidly, and filled with extinguishing water. Quick action venting stations are used for this purpose.
Simple quick action venting stations have been known and used for a long time. Thus DE 100 15 030 A1 describes a quick action venting valve for rapidly venting pipe systems of sprinkler installations in case of fire, in which a solenoid valve is arranged in the area of the control line leading to the diaphragm chamber of the quick opener, whereby the diaphragm chamber and thus the control chamber on the solenoid valve are unloaded by a direct pathway, which makes it possible to vent the sprinkler pipework more quickly.
Another solution for quick venting of a sprinkler installation is described in DE 199 36 454 A1 with a method for operating a sprinkler installation in a cold room, wherein the extinguishing valve is controlled by a release valve which is readjusted by the fire detection panel, in such a manner that the extinguishing valve opens the path for the liquid extinguishing medium into the feed line only if due to open sprinklers the gas pressure in the feed line is reduced and additionally the release valve opens.
An electrically controlled quick action vent for a dry pipework with sprinklers is also described in DE 10 2007 049 588 A1, wherein, on the dry pipework with sprinklers and dry pipe alarm valve, a solenoid valve is arranged, which is released by means of an extinguishing control panel and a pressure switch. The solution has the advantage that dry sprinkler networks can be vented rapidly and reliably even in case of foam admixtures with extinguishing water and the presence of remainders of extinguishing water, until the entire pipework is filled with extinguishing agent.
In special cases, preaction dry valve stations are used for quick opening of the pipes. A preaction dry installation controlled with this dry valve station represents a combination fire detection and sprinkler installation. It prevents the outflow of water in case of accidental damage to a sprinkler. For extinguishing water to be able to flow out of these dry installations, the fire detection installation must respond in addition.
Preaction dry stations, when actuated by a fire detection installation, must open, and release the water flow at the latest 15 s after actuation. If a sprinkler opens without actuation by the fire detection installation, the preaction dry station must not release the water flow. A pressure decrease in the dry pipework must continue to be reported. If the fire detection installation fails, or has a fault, the station must by switched over via a solenoid valve that is open without electricity, in such a way that it opens in case of dropping air pressure in the sprinkle pipework, i.e., in such a manner that it is analogous to a dry station in term of its function. The ratio of water pressure to air pressure (opening pressure) must be at least 5:1. The operating air pressure in the sprinkler pipework should be at most 3.5 bar.
In cases where the station is switched over in such a manner that it opens in case of dropping air pressure in the sprinkler pipework, i.e., it is switched over to pressure dependent operation, the air must escape through the opened sprinkler from the pipework until the air pressure has dropped to ⅕ of the supply pressure, so that the pipework is flooded, and water can reach the sprinkler. If the pipeworks are sufficiently large, this can take relatively long, which delays the extinguishing process.
Previous solutions to flood the pipework consisted in installing so-called quick action vents at the end of the pipework. In case of a pressure drop in the pipework, they open and allow air to escape from the pipework over a larger cross section. As a result, a more rapid pressure drop is achieved, which reduces the time until the opening pressure (⅕ of the supply pressure) is reached. From this time on, the pipework is then flooded
DE 43 20 442 A1 describes a generic dry pipe alarm valve with a quick opener, which is connected to the preaction dry pipe alarm valve when the preaction chamber is depressurized, and which, in the case of a decreasing pressure in the sprinkler pipework, opens the valve head of the dry pipe alarm valve, so that extinguishing water can flow into the dry pipework.
These installations have the disadvantage that, in addition, a quick action vent has to be installed in the pipework, and long flooding times are required to release the sprinklers.